1. Field of the Invention
The invention relates to a method for determining the integrity of memory and more particularly, to a method for determining the integrity of defective memory under a plurality of operating environments.
2. Description of the Prior Art
An essential component in today's electronic devices, such as switches, routers, or the like, is memory, such as a header table or a packet buffer. Because of the important role that memory plays in electronic devices, it is standard practice to only use memory that is free from defects in electronic devices. However, it is not to say that memory must be defective free in order to be incorporated for use. Given the right techniques, manufacturers could use memory with defective sections in a product and still have the product retain the same functionality as a product that uses defective free memory.
However, before a defective memory is employed in the use of a product, a manufacturer should be certain about the memory's integrity. That is to say, a manufactured memory should have consistency throughout a certain range of operating environment condition settings. In this case, a memory with integrity is a memory in which the number of defects and their respective locations are consistent under all the operating environments an electronic device is intended to perform under. For example, imagine a product is intended to run under two operating environments in regards to a voltage condition—low and medium. After testing processes it is discovered that a defective memory that the manufacturer plans to use in the product has two defects one at section 1, the other at section 5—when under a low voltage environment. In order for the memory to be declared as having integrity, the memory would have the two defects at the same sections when under a medium voltage environment. Any other case, and the memory lacks integrity (For example, there are three defects under the medium voltage, or there are two defects but one is at section 3 and the other at section 6).
A defective memory's integrity is important to check because a defective memory lacking integrity and used in an electronic device can cause operating problems in the electronic device. For example, imagine a memory lacking integrity is used inside a switch, such as a header table memory or a packet buffer memory used in a switch; the number of defects increases when the circuits (including the memory) of the switch operate above a threshold temperature. When the switch is first turned on, the circuits are below the threshold temperature. However, after operating for a certain amount of time, the circuits of the switch reach the threshold temperature. The switch then tries to access a section of the memory that was accessible when under the threshold temperature but now has become defective because the threshold temperature has been reached, resulting in malfunction, e.g. difficulty in forming and utilizing a linked list associated with the header table or the packet buffer.